Novel organometallic complexes which emit in the red to green spectral region and their use in oleds

ABSTRACT

Organometallic complexes which bear at least one ligand which has a unit having a triplet energy of at least 22 000 cm −1 , a process for preparing the organometallic complexes, a mixture comprising at least one inventive organometallic complex, the use of the organometallic complexes or of the mixture in organic light-emitting diodes, the organometallic complexes preferably being used as emitter materials, and specific nitrogen- or phosphorus-substituted triphenylene derivatives and a process for their preparation.

The present invention relates to organometallic complexes which bear atleast one ligand which has a unit having a triplet energy of at least 22000 cm⁻¹, to a process for preparing the organometallic complexes, to amixture comprising at least one inventive organometallic complex, to theuse of the organometallic complexes or of the mixture in organiclight-emitting diodes, the organometallic complexes preferably beingused as emitter materials, and to specific nitrogen- orphosphorus-substituted triphenylene derivatives and to a process fortheir preparation.

Organic light-emitting diodes (OLEDs) exploit the property of materialsto emit light when they are excited by electrical current. OLEDs are ofparticular interest as an alternative to cathode ray tubes andliquid-crystal displays for the production of flat visual display unitsand as a particularly efficient light source. Owing to the very compactdesign and the intrinsically low power consumption, devices comprisingOLEDs are suitable especially for mobile applications, for example forapplications in cellphones, laptops, digital cameras, etc.

The basic principles of the way in which OLEDs function and suitableconstructions (layers) of OLEDs are known to those skilled in the artand are specified, for example, in WO 2005/113704 and the literaturecited therein. The light-emitting materials (emitters) used may, as wellas fluorescent materials (fluorescence emitters), be phosphorescentmaterials (phosphorescence emitters). The phosphorescence emitters aretypically organometallic complexes which, in contrast to thefluorescence emitters which exhibit singlet emission, exhibit tripletemission (triplet emitters) (M. A. Baldow et al., Appl. Phys. Lett.1999, 75, 4 to 6).

For quantum-mechanical reasons, when the triplet emitters(phosphorescence emitters) are used, up to four times the quantumefficiency, energy efficiency and power efficiency are possible. Inorder to implement the advantages of the use of the organometallictriplet emitters in practice, it is desirable to provide emittermaterials which are notable for a good stability, a high luminescenceefficiency, a high color purity and suitable solubilities.

The prior art proposes numerous different materials for use as emittermaterials in OLEDs. Among the proposed materials are also transitionmetal complexes which exhibit phosphorescence.

For instance, US 2002/0034656 A1 relates to a light-emitting layer of anOLED, which comprises a phosphorescent organometallic compound, forincreasing the quantum efficiency of the OLED. Particularly suitableemitter materials are, according to US 2002/0034656 A1, phosphorescentorganometallic complexes of platinum, iridium or osmium, very particularpreference being given to using cyclometalated phosphorescent platinum,iridium or osmium complexes. Examples of suitable phosphorescenttransition metal complexes mentioned are Ir(ppy)₃ and platinum(II)complexes with bis[2-(2-phenyl)pyridinato-N,C2],bis[2(2′-thienyl)pyridinato-N,C3] or bis[benzo-(h)quinolinato-N,C].

In addition, known emitter materials are suitable phosphorescent Ircomplexes of the general formulae

from American Dyesource (www.adsdyes.com) (compounds ADS 075RE and ADS076RE). However, these complexes exhibit a strong red shift of theemission.

It is an object of the present invention to provide emitter materialsfor OLEDs, which exhibit a good thermal stability and are suitable forproducing OLEDs with good efficiency and high color purity.

This object is achieved by the provision of organometallic complexes ofthe general formula (I)

M[L₁]_(q)[L₂]_(r)[L₃]_(s)   (I)

in which

-   -   M is a metal atom;    -   L₁ is a ligand which may be uncharged, mono- or dianionic and        mono- or bidentate and is preferably a monoanionic bidentate        ligand based on a compound of the formula (II)

-   -   -   in which:        -   R¹ is an N-comprising radical,

is a unit having a triplet energy of at least 22 000 cm⁻¹;

-   -   -   L₂ is a mono- or dianionic ligand which may be mono- or            bidentate;        -   L₃ is an uncharged mono- or bidentate ligand;        -   q is the number of ligands L₁, where q is 1, 2 or 3 and the            ligands L₁, when q>1, may be the same or different;        -   r is the number of ligands L₂, where r is from 0 to 4 and            the ligands L₂, when r>1, may be the same or different;        -   s is the number of ligands L₃, where s is from 0 to 4 and            the ligands L₃, when s>1, may be the same or different;

where the sum of q+r+s depends on the oxidation stage and coordinationnumber of the metal M used and on the density of the ligands L₁, L₂ andL₃ and also on the charge of the ligands L₁ and L₂.

The organometallic complexes of the formula (I) according to the presentinvention feature outstanding efficiencies when used in OLEDs,especially because they may be present in high concentration in thelight-emitting layer of an OLED, and it is possible to suppress theformation of dimers and hence the quenching of the excited state.

Furthermore, when the inventive organometallic complexes are used,emissions with high color purity can be achieved, and the organometalliccomplexes according to the present invention have a high thermalstability.

The inventive organometallic complexes comprise at least one unit havinga triplet energy of at least 22 000 cm⁻¹ (determined by alow-temperature photoluminescence measurements), preferably having atriplet energy of from 22 000 cm⁻¹ to 28 230 cm⁻¹, more preferably from22 000 to 25 000 cm⁻¹. In the context of the present application, thetriplet energy is understood to mean the energy of the first tripletlevel.

The ligand L₁ in the inventive organometallic complexes of the formula(I) preferably has a triplet energy of at least 16 000 cm⁻¹, preferablyfrom 16 000 cm⁻¹ to 19 500 cm⁻¹, more preferably from 16 000 to 18 500cm⁻¹.

The inventive organometallic complexes generally exhibitelectroluminescence in the visible range of the electromagneticspectrum, preferably from 400 nm to 800 nm, more preferably from 450 nmto 800 nm, most preferably from 490 nm to 750 nm.

The R¹ radical in the ligand L₁ based on a compound of the formula (II)is, in accordance with the invention, an N-comprising radical. Theradical is preferably a heterocyclic radical which may be substituted orunsubstituted, more preferably an N-heterocyclic radical which comprisesat least one nitrogen atom. Most preferably, the R¹ radical is a mono-,bi- or tricyclic heteroaromatic radical which may be substituted orunsubstituted. The R¹ radical is very especially preferably a pyridyl orbenzothiazyl radical or a triazolyl radical, an isoxazolyl radical or apyrazolyl radical, which may be substituted or unsubstituted. Suitablesubstituents of the R¹ radical are the suitable substituents mentionedbelow. In a very particularly preferred embodiment, the R¹ radical isunsubstituted, i.e. all substitutable positions of the R¹ radical aresubstituted by hydrogen atoms.

The unit having a triplet energy of at least 22 000 cm⁻¹ in the ligandL₁ based on a compound of the formula (II) may be any unit which isknown to those skilled in the art, has the triplet energy mentioned andis suitable for forming organometallic complexes. The unit is preferablya unit based on triphenylene or a derivative thereof, such that thecompound of the formula (II), on which the ligand L₁ is based,preferably has the general formula (IIa)

in which the R¹ radical is as already defined above and the furtherradicals and indices are each defined as follows:

-   -   R², R³,    -   R⁴ are each independently C₁-C₂₀-alkyl,        C₀-C₂₀-alkylene-C₃-C₁₈-cycloalkyl,        C₀-C₂₀-alkyleneheterocycloalkyl having from 3 to 18 ring atoms,        C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, C₀-C₂₀-alkylene-C₆-C₁₈-aryloxy,        C₀-C₂₀-alkylene-C₆-C₁₈-aryl, C₀-C₂₀-alkyleneheteroaryl having        from 5 to 18 ring atoms, where the aforementioned radicals may        be substituted by hydroxyl, halogen, pseudohalogen, alkyl,        cycloalkyl, heterocycloalkyl, aryl, heteroaryl, amino, —C(O)R′,        —C(O)OR″, —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are        each independently hydrogen, alkyl, cycloalkyl,        heterocycloalkyl, aryl, heteroaryl or amino, or be        unsubstituted; hydroxyl, halogen, pseudohalogen, phosphonate,        phosphate, phosphine, phosphine oxide, phosphoryl, sulfonyl,        sulfonate, sulfate, amino, polyether, silyl-C₁-C₂₀-alkyl,        silyl-C₀-C₂₀-alkylene-C₆-C₁₈-aryl,        silyl-C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, —C(O)R′, —C(O)OR″,        —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are each        independently hydrogen, alkyl, cycloalkyl, heterocycloalkyl,        aryl, heteroaryl or amino;        -   R², R³ and R⁴ are preferably each independently            C₁-C₂₀-alkyl, preferably C₁-C₆-alkyl;            C₀-C₂₀-alkylene-C₃-C₁₈-cycloalkyl, preferably            C₀-C₆-alkylene-C₅-C₆-cycloalkyl;            C₀-C₂₀-alkyleneheterocycloalkyl having 3-18 ring atoms,            preferably C₀-C₆-alkyleneheterocycloalkyl having 5 or 6 ring            atoms; C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, preferably            C₀-C₆-alkylene-C₁-C₈-alkoxy; C₀-C₂₀-alkylene-C₆-C₁₈-aryloxy,            preferably C₀-C₈-alkylene-C₆-aryloxy;            C₀-C₂₀-alkylene-C₆-C₁₈-aryl, preferably            C₀-C₆alkylene-C₆aryl; C₀-C₂₀-alkyleneheteroaryl having 5-18            ring atoms, preferably C₀-C₆-alkyleneheteroaryl having 5 or            6 ring atoms, where the radicals mentioned may be            unsubstituted or substituted, preferred substituents being            alkyl, preferably C₁-C₈-alkyl; alkoxy, preferably            C₁-C₈-alkoxy; halogen, preferably F, Cl, Br, I, more            preferably F, Cl; or pseudohalogen, preferably CN, SCN, OCN,            N₃, CNO, SeCN, more preferably CN, SCN;        -   o is from 0 to 3, where the R³ radicals, where o>1, may be            the same or different;        -   n, p are each independently from 0 to 2, where the R² or R⁴            radicals, when n or p>1, may be the same or different;        -   X² is N, CH or CR²;        -   X³ is N, CH or CR³;        -   X⁴ are each independently N, CH or CR⁴.

In the context of the present application, the terms alkyl, alkylene,cycloalkyl, heterocycloalkyl, alkoxy, aryloxy, aryl, heteroaryl,halogen, pseudohalogen, amino, phosphonate, phosphate, phosphine,phosphine oxide, phosphoryl, sulphonyl, sulfonate, sulfate, polyether,silylalkyl, silylalkylenearyl and silylalkylenealkoxy are generally eachdefined as follows, particularly preferred definitions being specifiedin the specific definitions of the individual radicals:

Alkyl is understood to mean a radical having from 1 to 20 carbon atoms,preferably from 1 to 10 carbon atoms, more preferably from 1 to 8 carbonatoms, in the longest alkyl chain. This alkyl radical may be branched orunbranched and may optionally be interrupted by one or more heteroatoms,e.g. Si, N, or S, preferably N, O or S. In addition, the alkyl radicalmay be substituted by one or more substituents specified for the arylsubstituent specified below. The alkyl radicals are more preferablyselected from the group consisting of methyl, ethyl, isopropyl,n-propyl, n-butyl, sec-butyl, isobutyl, tert-butyl, and also CF₃.

A cycloalkyl radical is understood to mean a cyclic alkyl radical havinga base skeleton of from three to 18 carbon atoms, preferably from 5 to 8carbon atoms, more preferably 5 or 6 carbon atoms. Suitable baseskeletons are, for example, cyclopentyl or cyclohexyl. The base skeletonof the cycloalkyl radical may be unsubstituted (i.e. all carbon atomswhich are substitutable bear hydrogen atoms), or be substituted at one,more than one or all substitutable positions of the base skeleton.Suitable substituents are the substituents specified below for the arylradicals. Particularly preferred cycloalkyl radicals are cyclohexyl andcyclopentyl.

A heterocycloalkyl radical is understood to mean a radical having from 3to 18 ring atoms in the base skeleton, preferably 5 or 6 ring atoms. Inaddition, the heterocycloalkyl radical comprises at least one heteroatomselected from the group consisting of N, O and S. The heterocycloalkylradical may be substituted at one, more than one or all substitutablepositions of the base skeleton. Suitable substituents are thesubstituents specified for the aryl radicals.

Aryl is understood to mean a radical having a base skeleton of from 6 to18, preferably from 6 to 10, more preferably 6 carbon atoms, which isformed from an aromatic ring or a plurality of fused aromatic rings.Suitable base skeletons are, for example, phenyl, naphthyl, anthracenylor phenanthrenyl. This base skeleton may be unsubstituted (i.e. allcarbon atoms which are substitutable bear hydrogen atoms) or besubstituted at one, more than one or all substitutable positions of thebase skeleton. Suitable substituents are, for example, theaforementioned alkyl radicals, aryl radicals, preferably C₆-arylradicals, which may in turn be substituted or unsubstituted, heteroarylradicals, preferably heteroaryl radicals which comprise at least onenitrogen atom, more preferably pyridyl radicals or groups with donor oracceptor action. Suitable groups with donor or acceptor action arespecified below. Most preferably, the aryl radicals bear substituentsselected from the group consisting of methyl, F, Cl, CN, aryloxy andalkoxy. The aryl radical is preferably a C₆-C₁₈-aryl radical, morepreferably a C₆-C₁₀-aryl radical, most preferably a C₆-aryl radical,which is substituted by none, one or two of the aforementionedsubstituents, where, in the case of the C₆-aryl radical, the onesubstituent is arranged in the ortho-, meta- or para-position to thefurther bonding site of the aryl radical, and—in the case of twosubstituents—they may each be arranged in the meta-position orortho-position to the further bonding site of the aryl radical, or oneradical is arranged in the ortho-position and one radical in themeta-position, or one radical in the ortho- or meta-position and thefurther radical in the para-position.

A heteroaryl radical is understood to mean a radical which has from 5 to18 ring atoms, preferably 5 or 6 ring atoms. At least one of the ringatoms is a heteroatom, preferred heteroatoms being selected from thegroup consisting of N, O and S. The heteroaryl radical preferably hasone or two heteroatoms. The base skeleton is more preferably selectedfrom carbazole, pyridine, pyrrole, furan, pyrazole, imidazole andthiophene. The base skeleton may be substituted at one, more than one orall substitutable positions of the base skeleton. Suitable substituentsare the same as have already been specified for the aryl group.

An alkoxy group is understood to mean an O-alkyl group, where the alkylradical may be defined as specified above. One example of a preferredalkoxy group is OMe.

An aryloxy group is understood to mean an O-aryl group, suitable arylgroups being specified above. One example of a suitable aryloxy group isa phenoxy group.

The expression “C₀-C₂₀-alkylene” is understood to mean that thecorresponding radicals or groups may be bonded directly to the baseskeleton (C₀-alkylene) or may be bonded to the base skeleton via analkylene group having from 1 to 20 carbon atoms, preferably from 1 to10, more preferably from 1 to 6, most preferably 1 or 2 carbon atoms(C₁-0₂₀-alkylene, preferably C₁-C₁₀-alkylene, more preferablyC₁-C₆-alkylene, most preferably C₁-C₂-alkylene). The alkylene radicalcorresponds to the aforementioned alkyl radicals with the differencethat the alkylene radical has two bonding sites to further groups. Forexample, preferred C₀-C₂₀-alkylene-C₆-C₁₆-aryl radicals are benzylradicals.

In the context of the present application, a group having donor oracceptor action is understood to mean the following groups:

Groups having donor action are understood to mean groups which have a +Iand/or +M effect, and groups having acceptor action are understood tomean groups which have a −I and/or −M effect. Suitable groups havingdonor or acceptor action are halogen radicals, preferably F, Cl, Br, I,more preferably F, Cl, alkoxy radicals, aryloxy radicals, carbonylradicals, ester radicals, both oxycarbonyl and carbonyloxy, amineradicals, amide radicals, CH₂F groups, CHF₂ groups, CF₃ groups, CNgroups, thio groups, sulfonic acid groups, sulfonic ester groups,boronic acid groups, boronic ester groups, phosphonic acid groups,phosphonic ester groups, phosphine radicals, sulfoxide radicals,sulfonyl radicals, sulfide radicals, nitro groups, OCN, borane radicals,silyl groups, stannate radicals, imino groups, hydrazine radicals,hydrazole radicals, oxime radicals, nitroso groups, diazo groups,phosphine oxide groups, hydroxyl groups or SCN groups. Very particularpreference is given to F, Cl, CN, aryloxy and alkoxy.

Pseudohalogen is understood to mean a group selected from CN, SCN, OCN,N₃, CNO and SeCN, preferably CN or SCN.

Halogen is understood to mean a group selected from F, Cl, Br and I,preferably F or Cl.

The expression “amino” is an —NR₂ group in which each R radical isselected independently from hydrogen, C₁-C₆-alkyl, C₁-C₆-alkylene-C₆H₅and C₆-C₁₈-aryl, where the two R radicals may additionally, togetherwith the nitrogen atom, form a 4- to 6-membered, preferably 5- to6-membered, heterocyclic ring which may optionally be substituted byC₁-C₆-alkyl radicals, preferably C₁-C₆-alkyl, benzyl or phenyl.

Phosphonate is understood to mean —P(O)(OR)₂ groups in which the Rradicals are each selected independently from hydrogen, alkyl and aryl,preferably hydrogen, C₁-C₆-alkyl, phenyl and benzyl. In addition, the Rradicals may be a cation, e.g. Na⁺, K⁺, Mg²⁺ and Ca²⁺.

Phosphate is understood to mean —OP(O)(OR)₂ in which the R radicals areeach independently hydrogen, alkyl or aryl, preferably hydrogen,C₁-C₆-alkyl, phenyl or benzyl. In addition, the R radicals may be acation selected from Na⁺, K⁺, Mg²⁺ and Ca²⁺.

Phosphine is understood to mean —P(R₂) in which the R radicals are eachindependently hydrogen, alkyl or aryl, preferably hydrogen, C₁-C₆-alkyl,phenyl or benzyl.

Phosphine oxide is understood to mean —P(O)R₂ in which the R radicalsare each independently hydrogen, alkyl, aryl or amino, preferablyhydrogen, C₁-C₆-alkyl, phenyl, benzyl or —NR′₂ in which R′ are eachindependently hydrogen, alkyl or aryl, preferably hydrogen, C₁-C₆-alkyl,phenyl or benzyl.

Sulfonyl is understood to mean —S(O)₂R in which R is hydrogen, alkyl,aryl or amino, preferably hydrogen, C₁-C₆-alkyl, phenyl, benzyl or —NR′₂in which R′ are each independently hydrogen, alkyl or aryl, preferablyhydrogen, C₁-C₆-alkyl or benzyl.

Sulfonate is understood to mean —S(O)₂OR in which R is hydrogen, alkylor aryl, preferably hydrogen, C₁-C₆-alkyl, phenyl or benzyl. Inaddition, R may be a cation selected from Na⁺, K⁺, Mg²⁺ or Ca²⁺.

Sulfate is understood to mean —OS(O)₂OR in which R is hydrogen, alkyl oraryl, preferably hydrogen, C₁-C₆-alkyl, phenyl or benzyl. In addition, Rmay be a cation selected from Na⁺, K⁺, Mg²⁺ or Ca²⁺.

A polyether radical is understood to mean a group selected from the—(O—CHR)_(n)—OH and —(O—CH₂—CHR)_(n)—H groups, where R is selectedindependently from hydrogen, alkyl, aryl, halogen and n is from 1 to250.

Silyl-C₁-C₂₀-alkyl is understood to mean an SiR₃ group where the Rradicals are each hydrogen or alkyl, preferably C₁-C₆-alkyl or hydrogen.

Silyl-C₀-C₂₀-alkylene-C₆-C₁₈-aryl is understood to mean —SiR₃ groupswhere R is selected independently from aryl, preferably C₆-C₁₈-aryl,more preferably phenyl, where the aryl group is bonded directly to theSi(C₀-alkylene), and C₁-C₂₀-alkylenearyl groups, preferablyC₁-C₂₀-alkylene-C₆-C₁₈-aryl, more preferably C₁-C₆-alkylenephenyl.

A silyl-C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy group is understood to mean an—Si(OR)₃ group where a C₀-alkylene group is present, where the R radicalis a C₁-C₂₀-alkyl radical, preferably a C₁-C₆-alkyl radical. Inaddition, the group mentioned is understood to mean an—Si-C₁-C₂₀-alkylene-C₁-C₂₀-alkoxy group, preferably an—Si—C₁-C₆-alkylene-C₁-C₆-alkoxy group.

In the —C(O)R′, —C(O)R″, —OC(O)R′″, —C(O)OR″″ groups, R′, R″, R′″ andR″″ are each independently defined as hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl or amino, preferably hydrogen,C₁-C₆-alkyl, C₃-C₈-cycloalkyl, heterocycloalkyl having from three toeight ring atoms, C₆-C₁₈-aryl, preferably phenyl, heteroaryl having from5 to 18 ring atoms or amino as defined above.

A bidentate ligand is understood to mean a ligand which is coordinatedto the metal atom M at two points.

A monodentate ligand is understood to mean a ligand which is coordinatedto the metal atom M at one point on the ligand.

Depending on the coordination number of the metal M used and the natureand number of the ligands L₁, L₂ and L₃ used, it is possible fordifferent isomers of the corresponding metal complexes to be presentwith the same transition metal M and same nature and number of ligandsused. The present invention relates in each case to individual isomersof the transition metal complexes of the formula (I) and also mixturesof different isomers in any desired mixing ratio. In general, thedifferent isomers of the transition metal complexes of the formula (I)may be separated by processes known to those skilled in the art, forexample by chromatography, sublimation or crystallization.

In the compounds of the formula (IIa), the indices n, o and p may eachbe 0, 1, 2 or 3 (index o) or 0, 1 or 2 (indices n and p). In the casethat the indices n, o and p are 0, the corresponding substitutablepositions of the triphenylene skeleton or of a derivative thereof aresubstituted by hydrogen atoms.

Preferred embodiments of the R², R³ and R⁴ radicals have been specifiedabove. R², R³ and R⁴ are more preferably each C₁-C₄-alkyl, for examplemethyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl ortert-butyl, halogen-substituted C₁-C₄-alkyl, preferably F-substitutedalkyl, for example CF₃, C₁-C₄-alkoxy, for example OMe, OEt, OnPr, OiPr,OnBu, OsecBu, OiBu, OtertBu, halogen, preferably F or pseudohalogen,preferably CN.

The R², R³ and R⁴ radicals in the X², X³ and X⁴ groups eachindependently have the definitions specified above for the R², R³ and R⁴radicals.

In a preferred embodiment of the present invention, the radicals andindices in the triphenylene derivatives of the formula (II) are eachdefined as follows:

R¹ is an N-comprising radical, preferably a heterocyclic radical whichmay be substituted or unsubstituted, more preferably an N-heterocyclicradical comprising at least one nitrogen atom, most preferably a mono-,bi- or tricyclic heteroaromatic radical which may be substituted orunsubstituted, very especially preferably a pyridyl or benzothiazylradical or a triazolyl radical, an isoxazolyl radical or a pyrazolylradical, which may be substituted or unsubstituted;

-   -   R², R³,    -   R⁴ are each independently C₁-C₂₀-alkyl,        C₀-C₂₀-alkylene-C₃-C₁₈-cycloalkyl, C₀-C₂₀        alkyleneheterocycloalkyl having from 3 to 18 ring atoms,        C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, C₀-C₂₀-alkylene-C₆-C₁₈-aryloxy,        C₀-C₂₀-alkylene-C₆-C₁₈-aryl, C₀-C₂₀-alkyleneheteroaryl having        from 5 to 18 ring atoms, where the aforementioned radicals may        be substituted by hydroxyl, halogen, alkyl, cycloalkyl,        heterocycloalkyl, aryl, heteroaryl or amino, or be        unsubstituted; pseudohalogen or halogen, further preferred R²,        R³ and R⁴ radicals being specified above;    -   o is from 0 to 3, where the R³ radicals, when o>1, may be the        same or different;    -   n, p are each independently from 0 to 2, where the R² or R⁴        radicals, when n or p>1, may be the same or different;    -   X² is CH or CR²;    -   X³ is CH or CR³;    -   X⁴ are each independently CH or CR⁴.

In the compounds of the formula (II), X², X³ and X⁴ are most preferablyeach CH. In a further very particularly preferred embodiment, theindices n, o and p are each 0.

The metal atom M in the organometallic complexes of the general formula(I) is preferably a metal atom selected from the group consisting of Fe,Cu, Ni, Ru, Rh, Pd, Pt, Os, Ir, Re, Ag, Cu, Au, Hg, Cd, Nb, Zr, Ca, Cr,Mo, W, Mn, Tc, B, Al, Si, alkali metals and alkaline earth metals,preferably Ir, Co, Rh, Ni, Pd, Pt, Fe, Ru, Os, Cr, Mo, W, Mn, Tc, Re, Cuand Au, in any oxidation state possible for the corresponding metalatom. The metal atom M is more preferably selected from the groupconsisting of Ir, Rh, Ru, Pd and Pt, most preferably selected from thegroup of Ir, Pd and Pt. The metal atom M is very especially preferablyIr(III).

The R¹ radical is more preferably a radical of the formula

where Q is in each case independently CR^(a) or N, where at least one Qgroup in the ortho-position to the bonding site is N. In general, theaforementioned R¹ radical comprises a total of 1, 2, 3 or 4 nitrogenatoms, preferably 1, 2 or 3 nitrogen atoms, more preferably 1 or 2nitrogen atoms. The further ring members in the aforementioned R¹radical are carbon atoms. R^(a) is independently hydrogen, alkyl,cycloalkyl, heterocycloalkyl, aryl, heteroaryl, amino or a group havingdonor or acceptor action;

or a radical of the formulae

where Q is in each case independently CR^(a) or N, where at least one Qgroup in the ortho-position to the bonding site is N, and Q′ is CR^(a)₂, O, S or NR^(c). In general, the aforementioned R¹ radical (a)comprises a total of 1, 2, 3 or 4 nitrogen atoms, preferably 1, 2 or 3nitrogen atoms, more preferably 1 or 2 nitrogen atoms. Theaforementioned R¹ radical (b) generally comprises a total of 1, 2, 3 or4 nitrogen atoms, preferably 1, 2 or 3 nitrogen atoms, more preferably 1or 2 nitrogen atoms. It is likewise possible that the R¹ radical (b)comprises a total of 1, 2 or 3 nitrogen atoms and 1 oxygen atom or 1sulfur atom, preferably 1 or 2 nitrogen atoms and 1 oxygen atom or 1sulfur atom, more preferably 1 nitrogen atom and 1 oxygen atom or 1sulfur atom. The aforementioned R¹ radical (d) comprises generally atotal of 1, 2, 3 or 4 nitrogen atoms, preferably 1, 2 or 3 nitrogenatoms, more preferably 1 or 2 nitrogen atoms. The further ring membersin the aforementioned R¹ radicals are carbon atoms. R^(a), R^(b) andR^(c) are each independently hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl, amino, CF₃, CN, alkoxy or F.

Examples of suitable R¹ radicals are:

where R′, R″, R′″ and R″″ may each be as defined for R^(a).

In addition, the aforementioned R¹ radicals may additionally bear fusedgroups, preference being given to benzofusions. One example of asuitable benzofused R¹ radical is:

Examples of particularly preferred triphenylene derivatives of theformula II are specified below, where the triphenylene skeleton mayoptionally bear further substituents and/or one or more CH groups of thetriphenylene base skeleton may be replaced by N:

The ligand L₁ based on a compound of the general formula (II) may beuncharged, monoanionic or dianionic, and monodentate or bidentate. Theligand L₁ in the organometallic complexes of the general formula (I) ispreferably a monoanionic bidentate ligand.

The organometallic complexes of the general formula (I) comprise one,two or three ligands L₁, where, in the case when more than one ligand L₁is present in the organometallic complexes of the formula (I), theligands L₁ may be the same or different. In one embodiment of thepresent invention, the organometallic complex of the general formula (I)comprises two ligands L₁. This means that q in the organometalliccomplexes of the general formula (I) is 1, 2 or 3, preferably 1 or 2,more preferably 2, where the ligands L₁, when q>1, may be the same ordifferent.

The ligand L₂ in the organometallic complexes of the general formula (I)is a monoanionic or dianionic ligand which may be monodentate orbidentate.

Suitable monoanionic or dianionic ligands L₂, which may be monodentateor bidentate, are ligands used customarily as monodentate or bidentate,monoanionic or dianionic ligands.

Suitable monoanionic monodentate ligands are, for example, halides,especially Cl⁻ and Br, pseudohalides, especially CN⁻, cyclopentadienyl(Cp⁻), hydride, alkyl radicals which are bonded to the metal M via asigma bond, for example CH₃, alkylaryl radicals which are bonded to themetal M via a sigma bond, for example benzyl.

Suitable monoanionic bidentate ligands are, for example, acetylacetonateand derivatives thereof, picolinate, Schiff bases, amino acids,arylacyl, for example phenylpyridine, and the further bidentatemonoanionic ligands specified in WO 02/15645, preference being given toacetylacetonate and picolinate.

Suitable dianionic bidentate ligands are, for example, dialkoxides,dicarbonates, dicarboxylates, diamides, diimides, dithiolates,biscyclopentadienyls, bisphosphonates, bissulfonates and3-phenylpyrazole.

Particularly preferred suitable ligands L₂ are the following ligands (a)to (f)

in which

-   -   R⁵ in each of the ligands (a) to (f) is independently hydrogen,        C₁-C₂₀-alkyl, C₀-C₂₀-alkylene-C₃-C₁₈-cycloalkyl,        C₀-C₂₀-alkyleneheterocycloalkyl having from 3 to 18 ring atoms,        C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, C₀-C₂₀-alkylene-C₆-C₁₈-aryloxy,        C₀-C₂₀-alkylene-C₆-C₁₈-aryl, C₀-C₂₀-alkyleneheteroaryl having        from 5 to 18 ring atoms, where the aforementioned radicals may        each be substituted by hydroxyl, halogen, pseudohalogen, alkyl,        cycloalkyl, heterocycloalkyl, aryl, heteroaryl, amino, —C(O)R′,        —C(O)OR″, —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are        each independently hydrogen, alkyl, cycloalkyl,        heterocycloalkyl, aryl, heteroaryl or amino, or be        unsubstituted; hydroxyl, halogen, pseudohalogen, phosphonate,        phosphate, phosphine, phosphine oxide, phosphoryl, sulfonyl,        sulfonate, sulfate, sulfone, amino, polyether,        silyl-C₁-C₂₀-alkyl, silyl-C₀-C₂₀-alkylene-C₆-C₁₈-aryl,        silyl-C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, —C(O)R′, —C(O)OR″,        —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are each        independently hydrogen, alkyl, cycloalkyl, heterocycloalkyl,        aryl, heteroaryl or amino;        -   R⁵ is preferably hydrogen, C₁-C₆-alkyl,            C₀-C₄-alkylene-C₃-C₈-cycloalkyl, C₀-C₄-alkylene-C₆-C₁₈-aryl;    -   X′ are each independently CR⁵ or N;    -   Y′ is C(R⁵)₂, NR⁵, O or S;    -   Y″ is N⁻;    -   n′ is 1, 2, 3 or 4;    -   o′ is 1, 2, 3, 4 or 5,    -   p′ is 1 or 2.

The ligand L₂ is most preferably selected from the group consisting ofβ-diketonates such as acetylacetonate and derivatives thereof,picolinate, amino acid anions and monoanionic bidentate ligands of thegeneral formula (b), where all X′ groups in the formula (b) are morepreferably N.

The wavy line in the ligands of the general formula (f) means that allpossible cis/trans isomers are encompassed by the general formula (f).

The inventive organometallic complexes of the formula (I) may have 0, 1,2, 3 or 4 ligands L₂. In the presence of more than one ligand L₂ in theorganometallic complexes of the formula (I), the ligands L₂ may be thesame or different. The organometallic complexes of the general formula(I) preferably have one or two ligands L₂. This means that r in theorganometallic complexes of the formula (I) is from 0 to 4, preferably 1or 2.

The organometallic complexes of the formula (I) may additionallyoptionally have one or more uncharged mono- or bidentate ligands L₃.

Suitable uncharged monodentate or bidentate ligands L₃ are preferablyselected from the group consisting of phosphines, both monophosphinesand bisphosphines; phosphonates, both monophosphonates andbisphosphonates, and derivatives thereof; arsenates, both monoarsenatesand bisarsenates, and derivatives thereof; phosphites, bothmonophosphites and bisphosphites; CO; pyridines, both monopyridines andbispyridines; nitriles, dinitriles, allyl, diimines, unconjugated dienesand conjugated dienes which form a π-complex with the metal M.Particularly preferred uncharged monodentate or bidentate ligands L₃ areselected from the group consisting of phosphines, both monophosphinesand bisphosphines, preferably trialkyl-, triaryl- oralkylarylphosphines, more preferably PAr₃, where Ar is a substituted orunsubstituted aryl radical and the three aryl radicals in PAr₃ may bethe same or different, more preferably PPh₃, PEt₃, PnBu₃, PEt₂Ph,PMe₂Ph, PnBu₂Ph; phosphonates and derivatives thereof, arsenates andderivatives thereof, phosphites, CO; pyridines, both monopyridines andbispyridines, where the pyridines may be substituted by alkyl or arylgroups; nitriles and dienes which form a π-complex with the metal M,preferably η⁴-1,4-dibenzyl-1,3-butadiene, η⁴-2,4-hexadiene,η⁴-3-methyl-1,3-pentadiene, η⁴-1,4-dibutyl-1,3-butadiene,η⁴-1,4-bis(trimethylsilyl)-1,3-butadiene and η² or η⁴-cyclooctadiene (ineach case 1,3 and 1,5), more preferably 1,4-diphenyl-1,3-butadiene,1-phenyl-1,3-pentadiene, 2,4-hexadiene, butadiene, η²-cyclooctene,η⁴-1,3-cyclooctadiene and η⁴-1,5-cyclooctadiene. Very particularlypreferred uncharged monodentate ligands are selected from the groupconsisting of PPh₃, P(OPh)₃, CO; pyridine, nitriles and derivativesthereof. Suitable uncharged monodentate or bidentate ligands arepreferably 1,4-diphenyl-1,3-butadiene, 1-phenyl-1,3-pentadiene,2,4-hexadiene, η⁴-cyclooctadiene and η²-cyclooctadiene (in each case 1,3and 1,5).

The organometallic complexes of the formula (I) may have 0, 1, 2, 3 or 4uncharged monodentate or bidentate ligands L₃. If more than 1 ligand L₃is present in the transition metal complexes of the formula (I), theligands L₃ may be the same or different. In a preferred embodiment, theorganometallic complex of the general formula (I) comprises 0 ligandsL₃. This means that s in the organometallic complexes of the generalformula (I) is from 0 to 4, preferably 0.

In a particularly preferred embodiment, the present invention relates toorganometallic complexes of the formula (I), in which

-   -   M is Ir(III);    -   L₂ is a monoanionic bidentate ligand, preferred monoanionic        bidentate ligands having already been specified above,    -   q is 1 or 2, preferably 2;    -   r is 1 or 2;    -   s is 0;    -   L₁ is a monoanionic bidentate ligand derived from a triphenylene        derivative of the formula (IIa), preferred triphenylene        derivatives having been specified above,

where the sum of q+r=3.

Particularly preferred organometallic complexes of the formula (I) areorganometallic complexes of the following formulae (Ia), (Ib) and (Ic)and (Id), (Ie) and (If)

The inventive organometallic complexes (I) can be prepared by allprocesses known to those skilled in the art.

In a preferred embodiment, the preparation is effected by

-   -   (a) reacting metal salts or metal complexes which comprise the        desired metal M and optionally comprise one or more ligands L₃        with a first ligand L₁ or L₂ to give metal complexes which bear        either one or more ligands L₁ or one or more ligands L₂, if        appropriate in addition to one or more ligands L₃;

(b) reacting the metal complexes obtained in step (a) with a secondligand L₁ when the metal complex obtained in step (a) comprises one ormore ligands L₂, or with one ligand L₂ when the metal complex obtainedin step (a) comprises one or more ligands L₁, to obtain anorganometallic complex of the formula (I), step (b) being dispensed within the case that the organometallic complex of the formula (I) does notcomprise any ligand L₂, i.e. when r in the organometallic complex of theformula (I) is 0.

The reaction conditions for the preparation of organometallic complexesproceeding from suitable ligands are known to those skilled in the art.

The inventive organometallic complexes of the formula (I) are suitableas emitter materials especially for use in OLEDs. In general, theemitter materials are used together with one or more suitable matrixmaterials. One advantage of the inventive transition metal complexes isthat, owing to their structure, they can be used in high concentrationsin OLEDs, especially in the light-emitting layer, without formation ofdimers and hence quenching of luminescence occurring. As a result, it ispossible to provide OLEDs with high luminescence efficiency and highlifetime of the light-emitting layer.

Typically, one or more organometallic complexes of the formula (I) arepresent in the light-emitting layer of an OLED, preferably together withone or more matrix materials. The concentration of the organometalliccomplexes of the formula (I) in the matrix materials is generallyfrom >0 to ≦100% by weight, preferably from ≧5 to ≦50% by weight, morepreferably from ≧10 to ≦30% by weight and most preferably from ≧11 to≦25% by weight, based on the light-emitting layer. The matrix materialor the matrix materials are correspondingly present preferably in aconcentration of from 0 to <100% by weight, preferably from ≧50 to ≦95%by weight, more preferably from ≧70 to ≦90% by weight, most preferablyfrom 75 to ≦89% by weight.

Suitable matrix materials are known to those skilled in the art.Examples of suitable matrix materials are published, for example, inOrganic Light-Emitting Materials and Devices (Optical Science andEngineering Series), Ed.: Z. Li, H. Meng, CRC Press Inc., 2006.

The present application further provides for the use of the inventiveorganometallic complexes of the formula (I) or of the inventive mixturescomprising at least one organometallic complex of the formula (I) inorganic light-emitting diodes. Preference is given to using theorganometallic complexes of the formula (I) in the light-emitting layerof organic light-emitting diodes.

The present invention further provides for the use of the inventiveorganometallic complexes of the formula (I) as emitter materials.

OLEDs and the construction of suitable OLEDs are known to those skilledin the art.

The present invention further provides a triphenylene derivative of thegeneral formula (IIa)

-   -   in which:    -   R¹ is an N-comprising radical, preferably a heterocyclic radical        which may be substituted or unsubstituted, more preferably an        N-heterocyclic radical comprising at least one nitrogen atom,        most preferably a mono-, bi- or tricyclic heteroaromatic radical        which has at least one nitrogen atom and may be substituted or        unsubstituted, very especially preferably a pyridyl or        benzothiazyl radical or a triazolyl radical, an isoxazolyl        radical or a pyrazolyl radical, which may be substituted or        unsubstituted;    -   R², R³,    -   R⁴ are each independently C₁-C₂₀-alkyl,        C₀-C₂₀-alkylene-C₃-C₁₈-cycloalkyl,        C₀-C₂₀-alkyleneheterocycloalkyl having from 3 to 18 ring atoms,        C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, C₀-C₂₀-alkylene-C₆-C₁₈-aryloxy,        C₀-C₂₀-alkylene-C₆-C₁₈-aryl, C₀-C₂₀-alkyleneheteroaryl having        from 5 to 18 ring atoms, where the aforementioned radicals may        be substituted by hydroxyl, halogen, pseudohalogen, alkyl,        cycloalkyl, heterocycloalkyl, aryl, heteroaryl, amino, —C(O)R′,        —C(O)OR″, —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are        each independently hydrogen, alkyl, cycloalkyl,        heterocycloalkyl, aryl, heteroaryl or amino, or be        unsubstituted; hydroxyl, halogen, pseudohalogen, phosphonate,        phosphate, phosphine, phosphine oxide, phosphoryl, sulfonyl,        sulfonate, sulfate, amino, polyether, silyl-C₁-C₂₀-alkyl,        silyl-C₀-C₂₀-alkylene-C₆-C₁₈-aryl,        silyl-C₀-C₂₀-alkylene-C₁-C₂₀-alkoxy, —C(O)R′, —C(O)OR″,        —OC(O)R′″, —OC(O)OR″″, where R′, R″, R′″ and R″″ are each        independently hydrogen, alkyl, cycloalkyl, heterocycloalkyl,        aryl, heteroaryl or amino;    -   o is from 0 to 3, where the R³ radicals, where o>1, may be the        same or different;    -   n, p are each independently from 0 to 2, where the R² or R⁴        radicals, when n or p>1, may be the same or different;    -   X² is N, CH or CR²;    -   X³ is N, CH or CR³;    -   X⁴ are each independently N, CH or CR⁴.

Preferred embodiments of the definitions of the radicals and indices R¹,R², R³, R⁴, n, o, p, X², X³ and X⁴ are specified above.

The inventive triphenylene derivatives may be prepared by a processcomprising the steps of:

-   -   (i) preparing an arylboronic acid or an arylboronic acid        derivative (V) by reaction, for example catalyzed reaction, for        which, for example, a Pd-comprising catalyst can be used, of an        aromatic compound of the formula IV which has been        functionalized with a Y group with a corresponding boron        compound:

-   -   -   in which        -   Y is halogen and        -   R⁵ is H, C₁-C₆-alkyl, or two R⁵ radicals form a diatomic            bridge between the oxygen atoms, where the atoms of the            bridge may be substituted or unsubstituted;

    -   (ii) palladium-catalyzed reaction of one equivalent of the        arylboronic acid or of the arylboronic acid derivative of the        formula V with a biphenyl derivative of the formula VI which has        been functionalized with two z groups to obtain a compound of        the formula VII

-   -   -   in which        -   z is halogen or OTf;

    -   (iii) palladium-catalyzed intramolecular cyclization of the        compound of the formula VII to obtain the desired triphenylene        derivatives of the formula IIb.

A preferred process for preparing inventive triphenylene derivatives inwhich R¹ is a 2-pyridyl radical is shown by way of example hereinafter.

X, Y, Z and S each represent one or more substituents, suitablesubstituents Y, Z and S corresponding to the substituents (R²)_(n),(R³)_(o) and (R⁴)_(p), which are each defined above. The X groupcorresponds to the substituents of the R¹ radical, preferredsubstituents being R^(a) and R^(b) which are defined above. Suitablesubstituents X, Y, Z and S are, for example, Me, tBu, CF₃, F and OMe.

In steps A, B and C in Scheme 1, a suitable arylboronic acid or asuitable arylboronic acid derivative (V) is prepared. First, an aromaticcompound of the formula (IV) functionalized with a Y group (in thepresent case Br) is prepared. In the present scheme, in which R¹ ispyridine, the compound of the formula (IV) is prepared by azo couplingof the corresponding aryl group functionalized with halogen (in thepresent case Br) with pyridine. The resulting compound of the formula(IV) (in the present scheme 2-(4-bromophenyl)pyridine) is converted,preferably by palladium-catalyzed reaction, to the correspondingarylboronic acid or the corresponding arylboronic acid derivative (V).Suitable reactions are known to those skilled in the art. In the presentscheme, 2-(4-bromophenyl)pyridine is reacted with bis(pinacolato)diboronin the presence of Pd(dba)₃ and tricyclohexyiphosphine in catalyticamounts in the presence of a base, KOAc.

The resulting arylboronic acid or the resulting arylboronic acidderivative of the formula (V) is reacted in step D (step (ii) of theprocess according to the invention) with a biphenyl derivative of theformula (VI) functionalized with two z groups. The z groups are halogenor OTf, in the present case in Scheme 1 Br. The reaction is effectedunder palladium catalysis. The palladium catalyst used in step D in thepresent Scheme 1 is preferably Pd(PPh)₄ in the presence of a base,Na₂CO₃.

To prepare the desired triphenylene derivative of the formula (IIa), apalladium-catalyzed intramolecular cyclization is effected in step E inScheme 1 (step (iii) of the process according to the invention). Thepalladium catalyst used in the present Scheme 1 is Pd(OAc)₂ in catalyticamounts in the presence of a base, K₂CO₃.

The palladium-catalyzed intramolecular cyclization for preparing thedesired triphenylene derivatives of the formula (IIa) which has beenperformed in step (iii) was to date unknown in the prior art. It hasbeen found that the direct synthesis of fused aromatic systems(triphenylene derivatives) is possible in this way.

A further route to the preparation of the inventive triphenylenederivatives of the formula (IIa) is possible proceeding from2-triphenylenecarboxylic acids, as shown in the general Scheme 2:

In step (i), 2-triphenylenecarboxylic acid is converted by processesknown to those skilled in the art to the corresponding acid chloride.The reaction can be effected with any chlorinating agent known to thoseskilled in the art, for example with thionyl chloride.

Subsequently, in step (ii), the resulting acid chloride is reacted, forexample, with o-aminothiophenol to obtain an inventive triphenylenederivative of the formula (IIa).

Scheme 2 is merely by way of example. The triphenylene skeleton may bearfurther substituents or some of the carbon atoms present in thetriphenylene skeleton may be replaced by nitrogen atoms.

The triphenylenecarboxylic acids used may be prepared by processes knownto those skilled in the art.

A further route to the preparation of the inventive triphenylenederivatives via 2-triphenylenecarboxylic acid is shown in scheme 3.Scheme 3 shows, by way of example, a process for preparing inventivetriphenylene derivatives of the formulae (Id) and (Ie). A route to thepreparation of 2-triphenylenecarboxylic acid is likewise shown in scheme3:

Suitable reaction conditions can be taken from analogous reactions inthe literature. Suitable literature with regard to the individual stepsspecified in scheme 3 is listed below. Particularly preferred reactionconditions are specified in the example part which follows.

a) and b) analogous to publication for dihydropyrene: D. M. Connor, S.D. Scott, D. M. Collard, Chr. L. Liotta, D. A. Schiraldi, J. Org. Chem.1999, 64, 6888-6890.

c) Analogous to publication via 3-methyl-4-nitrobenzoic acid: D. J.Sall, A. E. Arfesten, J. A. Bastian, M. L. Denney, C. S. Harms, J. Med.Chem., 1997, 40, 2843-2857.

d) Analogous to publication via3-(1-methyl-1,2,4-triazol-3-yl)azabicyclo[2.2.2]octane: H. J. Wadsworth,S. M. Jenkins, B. S. Orlek, F. Cassidy, M. S. G. Clark, F. Brown, G. J.Riley, D. Graves, J. Hawkins, Chr. B. Naylor, J. Med. Chem. 1992, 35,1280-1290.

e) and f) analogous to publication for iodobenzoic acid: S. E. Gibson etal. Chem. Eur. J. 2005, 11, 69-80.

g) Analogous to publication for benzaldehyde oxime: P. Aschwanden et al.Org. Lett. 2005, 7, 5741-5742.

h) Analogous to publication for 3-substituted isoxazoles: A. Baranski,Pol. J. Chem. 1982, 56, 1585-1589 and R. G. Micetich, Can. J. Chem.1970, 48, 467-476 and S.-R. Sheng, X.-L. Liu, Q. Xu, C.-S. Song,Synthesis 2006, 14, 2293-2296.

Scheme 3 is merely by way of example. The triphenylene skeleton may bearfurther substituents or some of the carbon atoms present in thetriphenylene skeleton may be replaced by nitrogen atoms.

A further route to the preparation of the inventive triphenylenederivatives proceeding from a triphenylene skeleton may proceed via abromination of triphenylene analogously to processes known to thoseskilled in the art. Scheme 4 shows this route by way of example for thepreparation of the triphenylene derivative of the formula (If):

Suitable reaction conditions can be taken from analogous reactions inthe literature. Suitable literature with regard to the individual stepsspecified in scheme 4 is listed below. Particularly preferred reactionconditions are specified in the example part which follows.

a) Analogous to publication by R. Breslow, Ronald B. Juan, Bernhard R.Q. Kluttz, C.-z. Xia, Tetrahedron 1982, 38, 863-867.

b) Analogous to publication for phenylpyrazole: J. C. Antilla, J. M.Baskin, T. E. Barder, S. L. Buchwald, J. Org. Chem. 2004, 69, 5578-5587.

c₁) Analogous to publication for dibromochlorobenzene: K. Menzel, L.Dimichele, P. Mills, D. E. Frantz, T. D. Nelson, M. H. Kress, Syn. Lett.2006, 12, 1948-1952.

c₂) Analogous to publication for tetrabromoaromatics: G. Dorman, J. D.Olszewski, G. D. Prestwich, Y. Hong, D. G. Ahem, David G. J. Org. Chem.1995, 60, 2292-2297.

c₃) Analogous to publication for debromination of aromatics: S. Arai, M.Oku, T. Ishida, T. Shioiri; Tetrahedron Lett. 1999, 40, 6785-6790.

Scheme 4 is merely by way of example. The triphenylene skeleton may bearfurther substituents or some of the carbon atoms present in thetriphenylene skeleton may be replaced by nitrogen atoms. In particular,it is also possible to prepare the corresponding inventive triphenylenederivatives of the formulae (Id) and (Ie) according to scheme 4.

In addition, the inventive triphenylene derivatives can be obtained byaryne coupling. A general scheme 5 is specified below. Scheme 5a showsthe preparation by aryne coupling using the example of the preparationof the compounds of the formulae (Id), (Ie) and (If):

The reaction conditions are analogous to the preparation ofmethyltriphenylene, as disclosed, for example, in Z. Liu, R. Larock, J.Org. Chem. 2007, 72, 223-232. Particularly preferred reaction conditionsare specified in the example part which follows.

The examples which follow provide additional illustration of theinvention.

EXAMPLES

Preparation of Triphenylene Derivatives of the Formula (IIa) Accordingto Scheme 1:

1. Preparation of 2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)pyridine

0.39 g (0.4 mmol) of Pd(dba)₃ and 0.28 g (1 mmol) oftricyclohexylphosphine are suspended in 10 ml of dry dioxane under anitrogen atmosphere. The resulting mixture is stirred at roomtemperature for 30 minutes. Subsequently, 5.3 g (15 mmol) ofbis(pinacolato)diboron, 2.1 g (21 mmol) of KOAc and 3.3 g (14 mmol) of2-(4-bromophenyl)pyridine are added gradually. The reaction mixture isboiled under reflux for 20 hours, cooled and treated with 10 ml of waterat room temperature. The product is extracted with dichloromethane. Thesolvent is removed under reduced pressure and the resulting crudeproduct is purified by means of a short silica gel column. Afterpurification by means of the silica gel column (dichloromethane/hexane,3:1), 82% of the desired product is obtained.

¹H NMR(CDCl₃): δ=1.37(s,12H), 7.22-7.26(m, 1H), 7.72-7.80(m, 2H),7.92(J=8.4 Hz, 2H), 8.02(J=8.2Hz, 2H), 8.71(J=4.9 Hz, 1H).

2. Preparation of a Diphenyl Derivative of the Formula (VI) Substitutedby Two Br Radicals

The preparation of substituted dibromides proceeds fromo-dibromobenzenes. A typical process comprises the reaction sequence oflithiation/coupling. A general process is disclosed in the followingreference: H. S. M. Kabir et al., J. Chem. Soc., Perkin Trans. 1, 2001,159-165 (synthesis of 2,2′-dibromo-4,4′,5,5′-tetramethylbiphenyl).

3. Coupling of the Arylboronic Acid Derivative (V) with the BiphenylDerivative of the Formula (VI) Functionalized with Two Br Radicals

6.4 mmol of the dibromide (VI) and 6.4 mmol of the arylboronic acidderivative (V) (2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)pyridine)are dissolved in 25 ml of toluene. 0.4 mmol of Pd(PPh₃)₄ and 10 ml of a4N solution of Na₂CO₃ are added, and the mixture is heated up to refluxunder nitrogen. The reaction mixture is heated under reflux for 6 hoursand cooled, the phases formed are separated, and the water phase isextracted with dichloromethane and dried. The solvent is removed underreduced pressure and the crude product is purified by means of a shortsilica gel column. After purification by column chromatography(dichloromethane/hexane, 2:1), the desired o-terphenyl derivative isobtained in from 40 to 50% yield.

4. Intramolecular Cyclization to the Triphenylene Derivative of theFormula (IIa)

2.87 mmol of the o-terphenyl derivative, 0.14 mmol of Pd(OAc)₂ and 5.7mmol of K₂CO₃ are heated in 7 ml of DMA at 135° C. for 24 hours under anitrogen atmosphere. The reaction mixture is cooled, treated with 5 mlof water and extracted with dichloromethane. The organic phase is dried,the solvent is removed under reduced pressure and the residue ispurified by means of a short silica gel column (dichloromethane). Aftercolumn chromatography (dichloromethane/hexane, 2:1), the desiredtriphenylene derivative (IIa) is obtained in from 35 to 40% yield.

5. Preparation of the Inventive Triphenylene Derivatives of the Formula(IIa) According to Scheme 2

0.8 g (2.9 mmol) of 2-triphenylenecarboxylic acid (prepared by processesknown to those skilled in the art) is suspended in 15 ml of chloroform.Subsequently, 4 ml of thionyl chloride are added, and the reactionmixture is brought to reflux under a nitrogen atmosphere. After stirringunder reflux for 3 hours, the clear solution is evacuated under reducedpressure and the solid residue is recrystallized from hexane/chloroform(10/1). The resulting acid chloride 2 is dissolved in 10 ml of dry1-methylpyrrolidinone, and 0.32 ml (2.9 mmol) of o-aminothiophenol isadded. The reaction mixture is stirred at 100° C. for three hours. Aftercooling, the solution is added to cold water and the mixture is adjustedto a pH of from 8 to 9 with 7 N aqueous ammonia. The precipitate formedis filtered, washed with water and purified by means of a short silicagel column (dichloromethane) to obtain 0.82 g (78%) of the desiredtriphenylene derivative (IIa) 3.

m.p.: 230 to 231° C.

6. Preparation of an Inventive Transition Metal Complex

is a heterocyclic R¹ radical, suitable heterocyclic R¹ radicals beingspecified above

General Method

0.83 mmol of the ligand 1 is suspended in 30 ml of 2-ethoxyethanol in anitrogen atmosphere while heating. 0.38 mmol of IrCl₃.3H₂O is added andthe resulting suspension is brought to reflux. Within 30 minutes, acolored precipitate appears. The reaction mixture is kept under refluxfor 24 hours and then cooled to room temperature. The precipitate iscollected by sedimentation in a centrifuge and washed intensively withmethanol (6×15 ml). After drying under high vacuum while heating (T=80°C.), the dichloro-bridged dimer 2 is obtained in from 80 to 90% yield.These complexes are sparingly soluble in customary organic solvents andare used further without further purification.

0.16 mmol of the dichloro-bridged dimer 2 is suspended in 10 ml of2-ethoxyethanol under a nitrogen atmosphere. 0.4 mmol of acetylacetoneand from 85 to 90 mg of Na₂CO₃ are added and the reaction mixture isstirred at 100° C. for five hours. The resulting suspension is cooled toroom temperature and diluted with water, and the colored precipitate iscollected by sedimentation in a centrifuge, washed intensively withwater/methanol (4/1.6×15 ml) and dried under high vacuum while heating(T=100° C.). After purification by column chromatography, the complex 3is obtained as a colored solid in from 70 to 80% yield.

The Ir complexes Ia and Ib are obtained by the method specified above:

7. Use of the Inventive Transition Metal Complex Ia and Ib in an OLED

The diode structure is as follows:

-   -   Glass substrate comprising 120 nm of indium tin oxide    -   Hole injection layer (PEDOT-PSS) 200 nm    -   Hole transport layer composed of MTDATA, undoped; 100 nm    -   Emission layer composed of alpha-NPD, comprising 9% (by weight)        of iridium complex Ia (Example 1) or Ib (Example 2) doped; 250        nm    -   Layer for hole blocking and for electron transport, TPBI, 100 nm    -   Electron injection layer (lithium fluoride) 450 nm    -   Cathode composed of aluminum, 70 nm

The results are summarized in the table which follows, Ir complex Iahaving been used in Example 1 and Ir complex Ib in Example 2:

Efficiency Example 1 Example 2 Emission maximum 589 nm 541 nm Efficiency12 lm/W at 1000 nit 32 lm/W at 1000 nit

8. Preparation of the Inventive Triphenylene Derivatives of the Formula(IIa) According to Scheme 3 8.1 Preparation of 2-triphenylenecarboxylicacid

Step a)

Triphenylene (1 equivalent) is reacted at 0° C. with 2.1 equivalents ofAlCl₃ and 21.0 equivalents of CH₃COCl in CH₂Cl₂. After stirring at roomtemp. for 3 hours, the reaction product (acetyltriphenylene) wasobtained in 97% yield, and is used in step b).

Step b)

The reaction product obtained in step a) is admixed with 2.2 equivalentsof I₂ (based on the crude yield of acetyltriphenylene) in pyridinesolvent at room temperature. Thereafter, the mixture is kept at refluxfor 45 min, and then a further portion of I₂ (1.0 equivalent) is added.After reflux for a further hour, NaOH, EtOH and water are added and thereaction mixture is heated to reflux for 2 h. 2-triphenylenecarboxylicacid is obtained in 76% yield (based on crude yield ofacetyltriphenylene, or 74% based on triphenylene).

8.2 Preparation of a Triphenylene Derivative of the Formula IId

Step c)

1 equivalent of 2-triphenylenecarboxylic acid from step b) is reactedwith PCl₅ (2.1 equivalents) and 1.2 equivalents of p-toluenesulfonamidein xylene, while the temperature in the course of the reaction is keptat 120° C. for 17 h. At 190° C., solvents and reagents are distilledoff. After cooling to 5° C., pyridine is added and the mixture issubjected to aqueous workup. The reaction product obtained in 52% yieldis used in step d).

Step d)

The reaction product obtained in step c) (1 equivalent) is admixed at 0°C. with gaseous HCl in ethanol. The mixture is stirred at roomtemperature for a further 24 hours. The solvent is removed almostcompletely. Subsequently, ethanol as the solvent, 1.3 equivalents ofMeNHNH₂ and 2.5 equivalents of NEt₃ are added. The mixture is stirred atroom temperature for 24 hours. At 0° C., the reaction volume is reducedto a quarter, HCO₂H is added and the EtOH is drawn off completely.Subsequently, after further HCO₂H has been added at room temperature andthe mixture has been refluxed for 2 hours, the triphenylene derivativeof the formula IId is obtained.

8.3 Preparation of a Triphenylene Derivative of the Formula IIe

Step e)

1 equivalent of 2-triphenylenecarboxylic acid from step b) is stirredwith 2.0 equivalents of BH₃THF in THF at room temperature for 16 hours.The reaction product is converted further after the aqueous workup instep f).

Step f)

The reaction product from step e) is reacted with MnO₂ (25.0equivalents, based on 2-triphenylenecarboxylic acid) in CHCl₃ as asolvent under reflux for 3 days. After filtration through Celite, thereaction product is converted further in step g).

Step g)

The reaction product from step f) is stirred with 3.3 equivalents (basedon 2-triphenylenecarboxylic acid) of H₂NOH.HCl and 9.0 equivalents ofNaOH in EtOH at room temperature for 1 hour and under reflux for 30 min.The reaction product (2-triphenylenealdoxime) obtained in 80-90% yieldis converted further in step h) after the aqueous workup.

Step h)

The reaction product from step g) is stirred with 1.0 equivalent (basedon 2-triphenylenealdoxime) of NCS in CHCl₃ for 30 min. Thereafter, themixture is admixed with vinyl bromide (1.0 equivalent, based on2-triphenylenealdoxime) and NEt₃ (1.1 equivalent) is added dropwise, toobtain, after stirring at room temperature for 12 hours and aqueousworkup, the triphenylene derivative of the formula IIe. Alternatively tovinyl bromide, vinyl acetate or phenyl vinyl selenide can be used, inwhich case an additional refluxing step is added before the workup whenvinyl acetate is used, while the use of vinyl selenide requires theaddition of 30% H₂O₂ at 0° C. before the workup (in this case therefluxing step is dispensed with).

9. Preparation of the Inventive Triphenylene Derivatives of the Formula(IIa) According to Scheme 4

Step a)

Triphenylene (1 equivalent) is brominated with 8 equivalents of Br₂ inthe presence of catalytic amounts of iron in nitrobenzene to obtain 80%brominated triphenylene derivative.

Step b)

The brominated triphenylene derivative (1 equivalent) is subsequentlystirred with 5-10 mol % of CuI, 20 mol % ofamine(N,N-dimethylcyclohexane-1,2-diamine or phenantroline), 1.0equivalent of pyrazol and 2.1 equivalents of base (K₂CO₃, CsCO₃ orNaOtBu) at 110° C. in toluene for 24 hours.

Step c)

The reaction product obtained in step b) is subsequently converted tothe triphenylene derivative of the formula IIf in step c1), in step c2)or in step c3):

c₁) iPrMgCl.LiCl; HCl; c₂) H₂, NEt₃, Pd(OH)₂/C; c₃) HCO₂H, NEt₃,P(oTol)₃, Pd(OAc)₂, DMF, 50° C., 24 h.

10. Preparation of the Inventive Triphenylene Derivatives of the Formula(IIa) According to Scheme 5a

1-trifluoromethanesulfonato-2-trimethylsilylbenzene (3 equivalents) isreacted with 1 equivalent of the appropriate iodoaromatic (see scheme5a), in the presence of 5 mol % of Pd(OAc)₂, 5 mol % of dppf and 4equivalents of CsF in toluene/acetonitrile, to obtain the desiredligands of the formulae IId), IIe) and IIf).

1. An organometallic complex of the general formula (I) M[L₁]_(q)[I₂]_(r)[L₃]_(s)   (I) in which M is a metal atom; L₁ is a ligand which may be uncharged, mono- or dianionic and mono- or bidentate and is preferably a monoanionic bidentate ligand based on a compound of the formula (II)

in which: R¹ is an N-comprising radical,

is a unit having a triplet energy of at least 22 000 cm⁻¹; L₂ is a mono- or dianionic ligand which may be mono- or bidentate; L₃ is an uncharged mono- or bidentate ligand; q is the number of ligands L₁, where q is 1, 2 or 3 and the ligands L1, when q>1, may be the same or different; r is the number of ligands L₂, where r is from 0 to 4 and the ligands L₂, when r>1, may be the same or different; s is the number of ligands L₃, where s is from 0 to 4 and the ligands L3 , when s>1, may be the same or different; where the sum of q+r+s depends on the oxidation stage and coordination number of the metal used and on the density of the ligands L₁, L₂ and L₃ and also on the charge of the ligands L₁ and L₂. 2-16. (canceled) 